What is single phase and three phase?
Single-phase supply uses one live wire at about 240 V; three-phase uses three live wires for larger loads. Also called 1-phase, 3-phase, 1-ph, 3-ph, phase.
- Plain English
- Official sources
- Bill terms A–Z
Single phase and three phase on your bill
Most small homes have single-phase supply. Homes with large loads, such as several ACs, have three-phase supply.
In Tamil Nadu, single phase is 240 V. Three phase is 415 V and applies above 4,000 W of connected load.
Fixed charges and meter rent are often higher for three phase. Kerala's meter rent is Rs 6 single phase and Rs 15 three phase.
A three-phase meter can show a separate reading for each phase.
Ask the discom about a change of phase when you add or remove large loads.
Related terms
Official sources
- TNERC Tamil Nadu Electricity Distribution Code (consolidated to 31-03-2024), reg. 26(1)
“Single-phase 2 wire 240 volts between phase and neutral for supply to a total connected load” - TNERC Tamil Nadu Electricity Distribution Code (consolidated to 31-03-2024), reg. 26(1)
“Three-phase 4 wire 415 volts between phases”
Read on 17 October 2026. Your State regulator’s rules and your discom’s bill have the final word.